title: Redox mechanism of S-nitrosothiol modulation of neuronal CaV3.2 T-type calcium channels.
abstract: T-type calcium channels in the dorsal root ganglia (DRG) have a central function in tuning neuronal excitability and are implicated in sensory processing including pain. Previous studies have implicated redox agents in control of T-channel activity; however, the mechanisms involved are not completely understood. Here, we recorded T-type calcium currents from acutely dissociated DRG neurons from young rats and investigated the mechanisms of CaV3.2 T-type channel modulation by S-nitrosothiols (SNOs). We found that extracellular application of S-nitrosoglutathione (GSNO) and S-nitroso-N-acetyl-penicillamine rapidly reduced T-type current amplitudes. GSNO did not affect voltage dependence of steady-state inactivation and macroscopic current kinetics of T-type channels. The effects of GSNO were abolished by pretreatment of the cells with N-ethylmaleimide, an irreversible alkylating agent, but not by pretreatment with 1H-(1,2,4) oxadiazolo (4,3-a) quinoxalin-1-one, a specific soluble guanylyl cyclase inhibitor, suggesting a potential effect of GSNO on putative extracellular thiol residues on T-type channels. Expression of wild-type CaV3.2 channels or a quadruple Cys-Ala mutant in human embryonic kidney cells revealed that Cys residues in repeats I and II on the extracellular face of the channel were required for channel inhibition by GSNO. We propose that SNO-related molecules in vivo may lead to alterations of T-type channel-dependent neuronal excitability in sensory neurons and in the central nervous system in both physiological and pathological conditions such as neuronal ischemia/hypoxia.
authors.affiliation: Department of Anesthesiology and Pain Medicine, College of Medicine, Busan Paik Hospital, Inje University, Busan, South Korea.
authors.forename: Jeonghan
authors.initials: J
authors.lastname: Lee
authors.forename: Michael T
authors.initials: MT
authors.lastname: Nelson
authors.forename: Kirstin E
authors.initials: KE
authors.lastname: Rose
authors.forename: Slobodan M
authors.initials: SM
authors.lastname: Todorovic
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020747:Calcium Channels, T-Type / Q000737:chemistry / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000187:drug effects / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects*; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D051381:Rats; D026422:S-Nitrosoglutathione / Q000494:pharmacology*
chemical_list: C509958:Cacna1h protein, rat; D020747:Calcium Channels, T-Type; D026422:S-Nitrosoglutathione